Make sure vegetables are at room temperature before putting them in the cooker which will lessen the time of exposure of the bottom potatoes to high heat while getting the cooker to pressure. If you have the cauliflower at low temp. it will take longer to get to full pressure which will tend to overcook the potatoes.

Heat a second burner to a low or medium heat and when the cooker is approaching full pressure move the cooker to the low or medium heat burner and time the cooking on this burner.

While the cooker is coming to pressure at high temperature pick up the cooker and occasionally swirl it to stir the materials within. To do this you should have confidence that the gasket will be okay.

Use a flame tamer.

On this recipe you might try adding an additional 1/2 cup of water to bring the liquid amount to the same as the recipe with coconut milk. This recipe calls for a quick release, did you do that? On the Magefesayou need only release the red safety lock for a quick release.

I used to burn food occasionally and now by using fresh vegetables at room temp., moving the cooker to a low to medium temp burner and occasionally swirling the cooker while it is heating to attain full pressure I no longer have the problem.

You might establish a temperature setting on the second burner by doing as Guy suggets in his post of July 6, 2004 and his link to Solving Foaming Problems in that link.